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CLC number: TV81

On-line Access: 2018-07-04

Received: 2017-04-14

Revision Accepted: 2017-10-13

Crosschecked: 2018-06-06

Cited: 0

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Citations:  Bibtex RefMan EndNote GB/T7714

 ORCID:

Jin-xiao Zhao

https://orcid.org/0000-0003-3484-8424

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Journal of Zhejiang University SCIENCE A 2018 Vol.19 No.7 P.544-556

http://doi.org/10.1631/jzus.A1700185


A simple method for calculating in-situ settling velocities of cohesive sediment without fractal dimensions


Author(s):  Jin-xiao Zhao, Guo-lu Yang, Monika Kreitmair, Yao Yue

Affiliation(s):  School of Water Resources and Hydropower Engineering, Wuhan University, Wuhan 430071, China; more

Corresponding email(s):   jxzhao@nhri.cn

Key Words:  Dredge, Sediment settling, Porosity, In-situ measurement, Density function


Jin-xiao Zhao, Guo-lu Yang, Monika Kreitmair, Yao Yue. A simple method for calculating in-situ settling velocities of cohesive sediment without fractal dimensions[J]. Journal of Zhejiang University Science A, 2018, 19(7): 544-556.

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author="Jin-xiao Zhao, Guo-lu Yang, Monika Kreitmair, Yao Yue",
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publisher="Zhejiang University Press & Springer",
doi="10.1631/jzus.A1700185"
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%A Monika Kreitmair
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T1 - A simple method for calculating in-situ settling velocities of cohesive sediment without fractal dimensions
A1 - Jin-xiao Zhao
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A1 - Yao Yue
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PB - Zhejiang University Press & Springer
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DOI - 10.1631/jzus.A1700185


Abstract: 
The settling velocity of sediment flocs is central to the study of the transportation process of contaminants in aqueous ecosystems. To describe the irregular shape of flocs, fractal theory based on the image analysis method is commonly used. However, this method usually leads to non-unique results as it requires the selection of a threshold intensity. Therefore, the main objective of this study is to develop a method to determine the settling velocity of both flocs and particles without using the fractal dimension. To achieve this goal, porosity was introduced as a substitute for the fractal dimension, and a simple method with three variables, floc diameter, mass concentration, and volume concentration of flocs, was developed. A density function method was used to obtain the floc porosity from a laser particle sizer which could obtain the volume concentration of sediment and an optical backscatter point sensor (OBS). Laboratory tests on two sediments from two different lakes were conducted. Results indicate that this method has a higher accuracy than traditional methods such as the Stokes equation and the Rubey equation. The variable density function performed better than the uniform density function and was, therefore, recommended for calculating the settling velocities for both micro and macro flocs. Using the developed method, the drag coefficient for the flocs was calculated and its accuracy analyzed. The method presented in this paper, which is simpler in determining in-situ settling velocities than traditional methods, also allows for direct inter-comparison between results derived from various studies.

不含分形维数的细颗粒泥沙沉速计算方法研究

目的:推导一种高精度、使用简单且不含有分形维数的细颗粒泥沙沉速计算方法,以应用于原位观测和实现不同计算结果间的相互比较.
创新点:1. 推导出了不含有分形维数的泥沙絮团沉速公式; 2. 将LISST等高精度仪器应用于泥沙絮团密度计算中.
方法:1. 通过理论推导,得到不含分形维数的粘性细颗粒泥沙沉速公式; 2. 通过试验对该公式的精度进行研究,并在此基础上研究不同密度计算方法对该公式精度的影响; 3. 研究不同沉速状态下,泥沙絮团的沉降规律.
结论:1. 通过对比实测沉速与计算沉速的结果可以看出,本文提出的絮团沉速公式在计算泥沙絮团的沉速时精度较高; 2. 通过比较两种不同密度计算方法的结果可以看出,变密度方法具有更高的精度; 3. 通过拟合结果可以看出,公式(15)中的参数η与泥沙所处的沉降区间有关,参数γ与泥沙自身的性质有关.

关键词:疏浚;泥沙沉速;孔隙率;原位观测;密度函数

Darkslateblue:Affiliate; Royal Blue:Author; Turquoise:Article

Reference

[1]Agrawal YC, Pottsmith HC, 2000. Instruments for particle size and settling velocity observations in sediment transport. Marine Geology, 168(1-4):89-114.

[2]Boyd PW, Trull TW, 2007. Understanding the export of biogenic particles in oceanic waters: is there consensus? Progress in Oceanography, 72(4):276-312.

[3]Brinke WBMT, 1994. Settling velocities of mud aggregates in the Oosterschelde tidal basin (the Netherlands), determined by a submersible video system. Estuarine, Coastal and Shelf Science, 39(6):549-564.

[4]Callens N, Minetti C, Coupier G, et al., 2008. Hydrodynamic lift of vesicles under shear flow in microgravity. EPL (Europhysics Letters), 83(2):24002.

[5]de Boer DH, Stone M, Levesque LM, 2000. Fractal dimensions of individual flocs and floc populations in streams. Hydrological Processes, 14(4):653-667.

[6]Delnoij E, Westerweel J, Deen NG, et al., 1999. Ensemble correlation PIV applied to bubble plumes rising in a bubble column. Chemical Engineering Science, 54(21):5159-5171.

[7]Dyer KR, Manning AJ, 1999. Observation of the size, settling velocity and effective density of flocs, and their fractal dimensions. Journal of Sea Research, 41(1-2):87-95.

[8]Falconer KJ, 1990. Fractal Geometry Mathematical Foundations and Applications. John Wiley & Sons, Hoboken, USA, p.499-500.

[9]Fettweis M, 2008. Uncertainty of excess density and settling velocity of mud flocs derived from in situ measurements. Estuarine, Coastal and Shelf Science, 78(2):426-436.

[10]Furukawa K, Wolanski E, Mueller H, 1997. Currents and sediment transport in mangrove forests. Estuarine, Coastal and Shelf Science, 44(3):301-310.

[11]Imre AR, 2006. Artificial fractal dimension obtained by using perimeter–area relationship on digitalized images. Applied Mathematics and Computation, 173(1):443-449.

[12]Jiang Q, Logan BE, 1991. Fractal dimensions of aggregates determined from steady-state size distributions. Environmental Science & Technology, 25(12):2031-2038.

[13]Kranenburg C, 1994. The fractal structure of cohesive sediment aggregates. Estuarine, Coastal and Shelf Science, 39(6):451-460.

[14]Maggi F, 2008. Projection of compact fractal sets: application to diffusion-limited and cluster-cluster aggregates. Nonlinear Processes in Geophysics, 15(4):695-699.

[15]Maggi F, 2013. The settling velocity of mineral, biomineral, and biological particles and aggregates in water. Journal of Geophysical Research: Oceans, 118(4):2118-2132.

[16]Maggi F, Manning AJ, Winterwerp JC, 2006. Image separation and geometric characterisation of mud flocs. Journal of Hydrology, 326(1-4):325-348.

[17]Markussen TN, Andersen TJ, 2013. A simple method for calculating in situ floc settling velocities based on effective density functions. Marine Geology, 344(4):10-18.

[18]Meakin P, 1991. Fractal aggregates in geophysics. Reviews of Geophysics, 29(3):317-354.

[19]Mikkelsen OA, Pejrup M, 2000. In situ particle size spectra and density of particle aggregates in a dredging plume. Marine Geology, 170(3-4):443-459.

[20]Rubey WW, 1933. Settling velocity of gravel, sand, and silt particles. American Journal of Science, s5-25(148):325-338.

[21]Shang QQ, Fang HW, Zhao HM, et al., 2014. Biofilm effects on size gradation, drag coefficient and settling velocity of sediment particles. International Journal of Sediment Research, 29(4):471-480.

[22]Smith SJ, Friedrichs CT, 2011. Size and settling velocities of cohesive flocs and suspended sediment aggregates in a trailing suction hopper dredge plume. Continental Shelf Research, 31(10):S50-S63.

[23]Sochan A, Bieganowski A, Ryżak M, et al., 2012. Comparison of soil texture determined by two dispersion units of Mastersizer 2000. International Agrophysics, 26(1):99-102.

[24]Spearman J, Bray RN, Land J, et al., 2007. Plume dispersion modelling using dynamic representation of trailer dredger source terms. Proceedings in Marine Science, 8:417-448.

[25]Sumer BM, Kozakiewicz A, Fredsøe J, et al., 1996. Velocity and concentration profiles in sheet-flow layer of movable bed. Journal of Hydraulic Engineering, 122(10):549-558.

[26]Vahedi A, Gorczyca B, 2011. Application of fractal dimensions to study the structure of flocs formed in lime softening process. Water Research, 45(2):545-556.

[27]Vahedi A, Gorczyca B, 2012. Predicting the settling velocity of flocs formed in water treatment using multiple fractal dimensions. Water Research, 46(13):4188-4194.

[28]Voulgaris G, Meyers ST, 2004. Temporal variability of hydrodynamics, sediment concentration and sediment settling velocity in a tidal creek. Continental Shelf Research, 24(15):1659-1683.

[29]Wilber D, Clarke D, 2001. Biological effects of suspended sediments: a review of suspended sediment impacts on fish and shellfish with relation to dredging activities in estuaries. North American Journal of Fisheries Management, 21(4):855-875.

[30]Zhang RJ, 1998. River Sediment Dynamics. China Water Power Press, Beijing, China, p.35-36 (in Chinese).

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